Screw-driver



I (No Model.) 28heets-Sheet1.

G. H. MALLETT & Z. T. FURBISH.

SCREW DRIVER. No. 275,235. Patented Apr. 3,1883.

lllmlmlmm ||L1 (No Model.) r 2 Sheets-Sheet 2. G. HMALLETT 8: Z. T.PURBISH.

SCREW DRIVER.

No. 275,235, Patented Apr. 3,1883.

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CHARLES H. MAL-LEFT AND ZACHARY T. FURBISH, OF AUGUSTA, MAINE.

SCREW DRIVER.

SPEOIFICATION'forming part of Letters Patent No. 275,235, dated April 3,1883. Application filed January 16, 1882. Renewed August 22, 1892. (X0model.)

To all whom it may concern:

Be it known that we, CHARLES H. MAL- LETT and ZACHARY T. FURBIsH, ofAugusta, in the county of Kennebec and State of Maine, have invented anew and useful Improvement in ScrewDrivers; and we do hereby declarethat the following is a full, clear, and exact description of the same.7

Our invention is an improvement in screwdrivers of that class in whichthe handle is provided with a clutch mechanism adapted to be reversed,so as to permit the handle to turn freely in either direction upon theshank, and to turn the shank in reverse movement, or to lock the handleto the shank against movement in both directions. The device, in itsmain features, is the same as shown in Letters Patent granted to us onthe 27th day of September, 1881.

The inventionconsists more particularly in the construction of the disk,which is keyed to the upper end of the shank, whereby a more secure holdor look is obtained; and, further, in the construction of the shit'terand 'the parts immediately connected therewith.

In the accompanying drawings, Figure 1 shows a side elevation of ourimprovedscrewdriver. Fig. 2 shows a section on line a: of Fig. 1. Fig. 3shows a section on line y 3 of Fig. 1. Fig. 4 shows a plan view with thetop removed. Fig. 5 is asection corresponding to Fig. 3, showing amodification. Fig. 6 is the plate adapted to that modification.

In these drawings, A represents a chamberedcasting, which forms a partof the enlarged upper end of the handle of the screwdriver, the castingbeing a sufficiently strong shell, having therein a nearly annularchamher to receive the disk a, keyed to the upper end of the shank b,which, when not locked, turns freely in the handle. This chamber isprovided with small lugs l 2 opposite each other, and each aquarter-turn removed from the central locking-notch, 1-, in the front ofthe wall of the chamber. at that point so as to contract the spacebetween the inner surface of said wall and the surface of the disk a,which in other parts is of uniform width, except at the rear oppositethe first thickening named, where the wall is The wall is thickenedthickened in a corresponding manner. Small steel rollers 6 and 7 on thefront and 8 and 9 on the rear are pressed forward by springs compressedbetween said rollers and the lugs, which springs, when free to act,press the rollers to cause them to bind in the narrowing space betweenthe disk and-the wall. In this respect the construction is notmaterially different from that shown in our patent aforesaid; but inorder more securely to lock the disk within the head when under thegreat strain sometimes put upon it when at work, we have formed the diskwith grooves or notches across its periphery, fitting the grooves ornotches to receive the small steel rollers. The parts are soproportioned that when the rollers are pressed forward they fit on oneside into the grooves and on the other bear against the thickened wall,thereby securely looking the parts against any possibility of turning. ehave shown four rollers, which is the preferred number; butfmanifestlytwo may be used instead of four. Upon the top of the plate we place theshifting ring 0, which has lugs 10 11, passing down between the pairs ofrollers on each side and fitted to the space, so that when the disk isturned to the right, for example, it will throw out the rollers 7 and 8,permitting the handle to turn in one direction freely and binding in theother, and when the plate is turned to the other side the reversemovement takes place; but when the shifting plate re mains in itscentral location all the rollers bear closely in the narrowed spaces,and the head is locked in both directions. This shifting ring is fittedexactly within the cavity of the head,so as to turn without binding, andis provided with notches 12 13, in which lie the extremities of aspring-plate, (I, made in theform shown, so as to be held withimthe ringby the shoulders thereon. The end of this plate projecting to the frontis slightly bent downward and provided with a small knob on the outside,by means of which it can be manipulated. This projecting end fits intonotches 3, 4, and 5 in the bottom of a shallow recess, 14, in the wallof the shell. The spring-plate (Z is held down by a small stud or screwin the center of the cap, adjusted to bear upon theplate; but bypressing down this little knob in front the spring can be raised out ofone notch and shifted sidewisc to another. This spring-plate and theconstruction of the shifting ring adapting it thereto constitute thispart of the improvement. These parts may all be cheaply made and veryreadily put together, and are not liable to get out of order. Small lugs16 17 are perforated to receive screws, which hold the cap upon theshell, thus completing the handle.

In Fig.5 wehave shown a modification of the chambered head A, in whichis a central circular opening for the disk which is lixed to the upperend of the shank of the driver, which disk nearly lills the circularspace. The steel rollers and their springs are located in small lateralpockets 24, .35, 26, and 27. Thesepock ets are setinclined, in themanner-shown, ncan ly tangentially to the ieriphery ot' the disk. Thepockets hold the springs and rollers in place, when the roller turnstoward the pocket in the direction shown by the arrow, and tends to pushthe roller back, while thereverse move ment binds and locks the disk.

Fig. 7 shows a plate having studs 21), 30, 5 and 52 fitted to pass intothe narrow annular space between the disk and the chamber, so that whenthe plate is turned it pushes back two of the rollers opposite eachother, in the manner heretofore explained. When the rollersare pressedforward by the springs the head is locked to the shank. The springs maybe coiled or bow springs, or of any suitable construction. Thisconstruction, though shown in connection with a screw-driver, isapplicable to a bit-stock or any equivalent article.

Having thus described our invention, what we claim is-- 1. Thecombination of thehandle,cha1nbered as described, with the grooved orserrated disk, fixed to the shank, and with the rollers and springs,adapted to bind against the walls and tointerlock with the serrations orgrooves, substantially as described.

2. The combination ot'the chambered head, the disk fixed to theshank,-the rollers, and their springs, with the shifting ring providedwith downwardly-projecting lugs, and the spring-plate adapted to lie innotches in said ring and to interlock with notches in the front wall,whereby the shifting ring is moved or held, substantially as described.

In testimony whereof we have signed our names to this specification inthe presence of two subscribing witnesses.

CHAS. H. \IALLETT. ZAOHARY T. FURBISH. Witnesses:

J. E. Panama, 7 S. LANCASTER.

